It rained real hard Tuesday night. Wednesday morning at about 5am I’m stumbling in my kitchen trying to make coffee and I hear a hissing noise outside.

“Hah”, I says to myself, “my neighbors are watering their lawn on an off day. They’ll get fined by the city if caught”.

The wife goes out to walk the dog, and when she returns she asks me why I’m watering the back yard.

Ruh roh.

One of the sprinkler zones in my back yard was running, and could have been running since we went to bed at 9:30pm the night before. They weren’t running prior to that when I let the dog out before retiring to bed, so it must have spontaneously started itself at some point in the night, meaning it could have been running for up to seven and a half hours!

The control box in the garage didn’t indicate that it was active. I did the first obvious step: I turned it off and on again. No luck. Next I cycled the system through all the zones hoping it would kick it into normal operation. No luck.

I hadn’t even had my coffee yet, so I wasn’t firing on all cylinders. I grabbed a flashlight and started popping open all the valve holes in my yard hoping to at least find the one that was stuck, not knowing what in the world I’d do if I even found it. I could only find four (of the six), and they were all in my front yard. Fortunately I came across one larger covered hole in my front yard and noticed it said “Irrigation” on the cover. Inside there was a master faucet, and closing it finally shut the water off.

This post is a bit of self-flagellation. I’ve been in this house for two years now, and there are LOTS of things (important things!) that I’m still totally unfamiliar with. I should have known about this master faucet. I knew the box was there, but I had assumed it was some electrical thing.

After a bit of Googling how sprinkler systems work, I came to the tentative conclusion that the solenoid that controls the valve for that sprinkler zone must have shorted out and got stuck on – probably due to the rain. Thinking on it more (because solenoids are very simple) this could mean that one of the lines going to the solenoid is always hot, and the control box activates that solenoid by closing the path to ground. Rainwater buildup could have provided a conductive path to ground. There’s probably a good reason that the control box provides the ground path, and not the hot path. Or I could be totally wrong how it works.

I called Collin County Sprinkler that Wednesday morning, and they had someone out this morning (Thursday). It took them 20 minutes to find the valve hole (using a fancy wire tracing tool) and fix it. They showed me a busted seal that let rainwater into the valve and up into the solenoid, and confirmed my “rainwater allowed path to ground” hypothesis (or they were just humoring me because I was asking a lot of annoying questions).

Fortunately my back yard slopes towards the alley so the excessive water didn’t get into the garage, and it’s hot outside so it evaporated very quickly. I don’t feel dumb not knowing where that valve was because it was very well hidden under the grass. There is one last valve I need to track down (which I forgot to ask about before they left), but I think I can find it on my own.

This incident is a big wake-up call for me. There are too many critical things in this house that I take on faith that they’re functional, and will stay functional – AC, plumbing, electricity, sprinklers, garage door, appliances, etc. I need to get a handle on those things. I don’t need to know every detail, but if something goes horribly wrong I need a plan.